—That must have been a lot of work.
—Yeah, it us three days to finish it.
A. takes
B. had taken
C. took
D. was taking
网友回答
A. takes
B. had taken
(答案→)C. took
D. was taking
解析：考查动词时态。句意：——你们一定做了许多工作。——是的，完成这些工作花费了我们三天的时间。根据“must have been”可知，此处是对过去情况的一种推测，故“花费”这一动作应发生在过去，所以用一般过去时。